The fractionation and accurate size characterization of biological colloids and macromolecules of high molecular weight will be pursued using the methods of sedimentation FFF, and where necessary, flow FFF. By developing specific procedures for a wide variety of sample types, whose separation/characterization presents challenges using conventional methodology, the project will seek to increase the usefulness of the FFF methods in biological characterization work. The combination of sedimentation FFF and quasi elastic light scattering holds particular promise for molecular weight characterization and the determination of particle size distributions of materials with unknown density. This mode of operation will be studied to enable the accurate characterization of spherical viruses, emulsions and liposomes. Steric FFF will be applied to the size-sorting of cells, whereby efforts will be made to minimize surface adhesion. Platelets will be fractionated for the purpose of correlating size with physiological activity, and HeLa cells will be sorted according to size in order to achieve synchronous populations of particles. Efforts will be made to render the fractionation type-specific through selective aggregation of desired cells. The replacement of the sedimentation field by an electrogravitational field will be explored in conjunction with cell separation.